Glyph Du Jour: November 2008 Archives

Glyph du Jour: Thermodynamic Q-dot

Q with Dot above in multiple fonts

This week, my Glyph du Jour is one that does NOT exist in Unicode. It's a capital Q with a dot above representing "heat transfer per unit time" (or rate of heat transfer). Similar thermodynamic symbols are (rate of work produced) and (rate of mass transfer)...and interestingly these DO exist in Unicode.

Why W-dot and m-dot, but no Q-dot? It's because these particular symbols probably have a use somewhere beyond thermodynamics. For instance, was sometimes used in older Classical Irish spelling (today's mh). Therefore the community was able to lobby for the inclusion of this letter within Unicode in order to transcribe historic Classical Irish texts (lucky for my thermodynamics course).

The irony here is that within Unicode Classical Irish actually has better resources than the engineering community (or the statistics community which could use p-hat or ). I don't think it's an evil conspiracy, but the fact that many engineers probably think of their notation quirks as a "font/layout" issue rather than as a "foreign language" issue.

The next step could be that someone proposes the inclusion of Q-dot or (and its sibling q-dot or which is rate of heat transfer per unit mass. This could raise the issue of whether we can get with just combining Q plus a "combining diacritic" dot - that is a manually combining a letter and a diacritic.

Based on what I've seen, I would say no. First, few everyday fonts support "combining accents" well. They would much rather work with precomposed characters with accents built in. partly because it is difficult to place a dot consistently for each letter without building it ahead. I can fudge a , but if I try , the dot often disappears into the taller capital Q. At best I'm stuck with Q ̇ (Q with upper-right dot).

Another lesson that someone WILL always find some new combination of the Latin alphabet to mess around with.

Dotted Letters & Combining Diacritic Test

Below is a table showing a test of the combining dot for the Q-dots and the existing dotted letters. As you can see, there are only a few dotted letters missing.
Note: Q-dots best viewed with Arial Unicode MS, Gentium or other specialized Unicode font.

Character Name Character Hex Entity Code Decimal Entity Code
Lower Q dot (Fudged) q+̇ q+̇
Capital Q dot (Fudged) Q+̇ Q+̇
Lower A with dot above ȧ ȧ ȧ
Capital A with dot above Ȧ Ȧ Ȧ
Lower B with dot above ḃ ḃ
Capital B with dot above Ḃ Ḃ
Lower C with dot above ċ ċ ċ
Capital C with dot above Ċ Ċ Ċ
Lower D with dot above ḋ ḋ
Capital D with dot above Ḋ Ḋ
Lower E with dot above ė #x0117; ė
Capital E with dot above Ė #x0116; Ė
Lower F with dot above ḟ ḟ
Capital F with dot above Ḟ Ḟ
Lower G with dot above ġ ġ ġ
Capital G with dot above Ġ Ġ Ġ
Lower H with dot above ḣ ḣ
Capital H with dot above Ḣ Ḣ
Capital I with dot above İ İ İ
Lower H with dot above ṁ ṁ
Capital H with dot above Ṁ Ṁ
Lower n with dot above ṅ ṅ
Capital N with dot above Ṅ Ṅ
Lower O with dot above ȯ ȯ ȯ
Capital O with dot above Ȯ Ȯ Ȯ
Lower P with dot above ṗ ṗ
Capital P with dot above Ṗ Ṗ
Lower R with dot above ṙ ṙ
Capital R with dot above Ṙ Ṙ
Lower S with dot above ṡ ṡ
Capital S with dot above Ṡ Ṡ
Lower T with dot above ṫ ṫ
Capital T with dot above Ṫ Ṫ
Lower W with dot above ặ ẇ
Capital W with dot above Ặ Ẇ
Lower X with dot above ẋ ẋ
Capital X with dot above Ẻ Ẋ
Lower Y with dot above ế ẏ
Capital Y with dot above Ế Ẏ
Lower Z with dot above ż ż ż
Capital Z with dot above Ż Ż Ż


About The Blog

I am a Penn State technology specialist with a degree in linguistics and have maintained the Penn State Computing with Accents page since 2000.

See Elizabeth Pyatt's Homepage ( for a profile.


The standard commenting utility has been disabled due to hungry spam. If you have a comment, please feel free to drop me a line at (

Powered by Movable Type Pro

Recent Comments